All,
As some of you may have found out, the next time you start ZPS you'll be greeted to a prompt telling you to convert to a "more efficient format". Doing so ATM will cause some unwanted issues, such as missing sounds/materials, excessive loading times, and so on.
The team's just been notified of this predicament, and are contacting Valve to figure out a way to resolve this problem ASAP.
We are sorry for any inconvenience caused by this issue.